Manivasagam, part of an organised crime gang, dumped the 11 bombs in the dustbin, they said.

Police said the surrender of the three persons came at a time when their investigations with the aid of CCTV footage from the area had narrowed down to the trio.

The trio were part of the organised crime gang operating in this part of the state, police said.

The 11 bombs were recovered from a dustbin in Anna Nagar area here on Nov 10.

Deputy Commissioner of Police Samant Rohan Rajendra had said the bombs were of 'grenade type' which would explode only when hurled hard against an object and had been dumped by organised crime members.

A low intensity cycle bomb had exploded in the same area on May 1, 2012, nine days ahead of the visit of top BJP leaders, including L K Advani to the city for a party meet.

In 2011, a powerful pipe bomb was found and defused from under a bridge near Tirumangalam in the district, hours before Advani was to take the route on his jan chetna yatra.

Police had said the Organised Crime Intelligence Unit got a tip off that the bombs had been left in the garbage bin. Even as police were rushing to the spot, a sanitary worker was picking the bombs as they looked mysterious.

Police recovered the bombs from her and sent it for expert analysis, which revealed they were grenade-type country bombs.